Selfing and inbreeding depression in seeds and seedlings of Neobalanocarpus heimii (Dipterocarpaceae)

Abstract

We evaluated the degree of selfing and inbreeding depression at the seed and seedling stages of a threatened tropical canopy tree, Neobalanocarpus heimii, using microsatellite markers. Selection resulted in an overall decrease in the level of surviving selfed progeny from seeds to established seedlings, indicating inbreeding depression during seedling establishment. Mean seed mass of selfed progeny was lower than that of outcrossed progeny. Since the smaller seeds suffered a fitness disadvantage at germination in N. heimii, the reduced seed mass of selfed progeny would be one of the determinants of the observed inbreeding depression during seedling establishment. High selfing rates in some mother trees could be attributed to low local densities of reproductive individuals, thus maintenance of a sufficiently high density of mature N. heimii should facilitate regeneration and conservation of the species.

Molecular and quantitative signatures of biparental inbreeding depression in the self-incompatible tree species Prunus avium

“…Seeds from one seed-tree (M3) even did not germinate. Loss of genetic diversity could be explained by a reduced fitness in seeds and seedlings leading to mortality, by instance through biparental inbreeding depression (Cheliak et al, 1985;Rajora et al, 2000;Hufford and Hamrick, 2003;Naito et al, 2005;Isagi et al, 2007;Duminil et al, 2009;Hasegawa et al, 2009). However, our data rather showed higher survival of offspring from related parents and fixation index showed excess of heterozygotes.…”

“…Loss of homozygote individuals seems indeed to be common in tree species (Cheliak et al, 1985;Hufford and Hamrick, 2003;Naito et al, 2005;Tamaki et al, 2009) and may result from very intensive competition for seedling establishment (Petit and Hampe, 2006) and heterozygote advantage (heterosis).…”

“…In self-compatible species with a mixed mating system, outcrossing rates tend to increase over life-stages because of late-acting selfincompatibility or inbreeding depression (Hufford and Hamrick, 2003;Naito et al, 2005;Ward et al, 2005;Ishida, 2006;Isagi et al, 2007;Naito et al, 2008;Hasegawa et al, 2009;Tamaki et al, 2009;Philipp and Nielsen, 2010;Kamm et al, 2011), that is, that offspring stemming from self-fertilization will experience reduced fitness. In obligate outcrossing species, biparental inbreeding (that is, mating of two genetically related individuals), might also reduce offspring viability and quality (Nason and Ellstrand, 1995;Teixeira et al, 2009).…”

Edge effects enhance selfing and seed harvesting efforts in the insect-pollinated Neotropical tree Copaifera langsdorffii (Fabaceae)

“…Thus, the higher levels of selfing may explain the low observed heterozygosity at the edge. However, in general, selfing in tropical tree species produces inbreeding depression, causing the mortality of selfed seeds and individuals as was observed in Eucalyptus argutifolia (Kennington and James, 1997), Eucalyptus marginata (Millar et al, 2000), Pseudobombax munguba (Gribel and Gibbs, 2002), Platypodium elegans (Hufford and Hamrick, 2003) and Neobalanocarpus heimii (Naito et al, 2005). We observed significant higher germination in the SW than the edge, suggesting that inbreeding depression was higher in seeds from the edge, where selfing was highest.…”

Remnant Pachira quinata pasture trees have greater opportunities to self and suffer reduced reproductive success due to inbreeding depression

“…Interestingly, the review by Lowe et al, (2005) found all studies showed a significant impact of fragmentation on fitness, with reduction in outcrossing rates. Although fitness losses may be driven by mate limitation (Naito et al, 2005), the exact cause is unclear and may vary by species and landscape context. The implications and significance of such fitness losses will depend on the extent to which inbred material survives regeneration.…”